Introducción
Thrombotic thrombocytopenic purpura is a rare disease characterized by microvascular thrombosis, the development of microangiopathic hemolytic anemia, kidney damage and neurological symptoms. The pathogenesis of TTP is based on deficiency of the metalloproteinase ADAMTS-13.

Caso
Male patient, 27 y.o., was admitted to the emergency department with weakness, headache, high body temperature (37.8 C), episode of loss of consciousness. Previous medical history was unremarkable. Patient was conscious, but answered to questions with delay. No focal neurological or meningeal symptoms were identified, no peripheral edema, rash, peripheral lymphnodes enlargement. Breathing was vesicular, no wheezing, respiratory rate 20 per minute; heart sounds were rhythmic, no murmur, BP 146/74 mm Hg, heart rate 83 per minute; abdomen was soft, painless; liver + 2 cm, the spleen wasn't palpable. Laboratory tests revealed normocytic, hyperchromic anemia (Hb 70), thrombocytopenia (53), leukocytosis (26.1), increase of creatinine (130.0 µmol/l), AST (72.5 U/l), total bilirubin (44.5 µmol/l) due to indirect fraction, D-dimer (1100 ng/ml) levels, decrease of folic acid level (1.5 ng/ml). Analysis of bone marrow punctate revealed a violation of detachment of platelets from megakaryocytes, hyperplasia of erythroid germ; CT scan of the brain - no pathological changes. Direct Coombs test was negative, CRP and procalcitonin levels were normal. 48 hours after admission, the patient’s condition progressively worsened, the patient became aggressive, speech disturbances appeared. The patient underwent a lumbar puncture (normal). Level of lactate dehydrogenase was examined (5094 units/l), schizocytes were detected in a blood smear (5%). Thrombotic microangiopathy was suspected, a blood test for ADAMTS-13 level was performed. The activity of ADAMTS-13 in the patient’s blood plasma was less than 1% of the level of ADAMTS-13 activity in control plasma obtained from healthy donors. Antibodies to metalloproteinase were detected in a low titer. Markers of systemic autoimmune diseases were negative. The patient was diagnosed with thrombotic thrombocytopenic purpura. Daily plasma exchange sessions, unfractionated heparin and pulse therapy with methylpredlnisolone 1000 mg/day for 3 days were urgently started. In 7 days of treatment clinical and laboratory tests were better and patient was referred to nephrology department.

Comentario
This clinical case demonstrates a rare disease with severe deficiency of the metalloproteinase ADAMTS-13 (less than 1%) with classic manifestations described in the literature. Plasma exchange and the administration of corticosteroids, started as soon as possible, made it possible to achieve an improvement in the patient’s condition, a hematological response, relief of neurological symptoms and prevent further progression of renal failure.

Conclusión
TTP is a serious and highly lethal disease, but with timely diagnosis and treatment, it is possible to cure patients.